Law of the River


Law of the River: A Timeline

  • 1869

    John Wesley Powell begins journey that is first to navigate the Colorado River and Grand Canyon by boat

  • 1889

    International Boundary and Water Commission is created between U.S. and Mexico

  • 1902

    Congress passes the Newlands Act, which creates the U. S. Bureau of Reclamation to help reclaim the arid West

  • 1903

    Salt River Valley Water Users Association is incorporated becoming the first multipurpose reclamation project authorized under the Newlands Act

  • 1905-1907

    Colorado River breaks through its banks during high flows and floods Imperial Valley creating the Salton Sea

  • May 13, 1907

    U.S. Supreme Court adopts the doctrine of equitable apportionment of benefits for rivers flowing between states. Kansas v. Colorado, 206 U.S. 46. The equitable apportionment doctrine is based on the “cardinal rule” of “equality of right” among states. “Each state stands on the same level with all the rest.” The Court later explains that “equality of right” refers “not to an equal division of the water, but to the equal level or plane on which all the states stand, in point or power and right, under our constitutional system.” Wyoming v. Colorado, 259 U.S. 419, 465 (1922).

  • 1911

    Arizona’s Theodore Roosevelt Dam completed 

  • 1912

    Yuma Project begins using Colorado River water

  • 1919

    Grand Canyon National Park created

    Seven basin states organize League of the Southwest in Salt Lake City to promote Colorado River development

  • 1921

    Congress approves renaming the Grand River above its confluence with the Green River as the Colorado River

    Congress authorizes the seven basin states to negotiate and enter into an interstate compact providing for the equitable division and apportionment of the Colorado River

  • Jan. 26, 1922

    The Colorado River Commission is organized at Washington, D.C.

  • 1922

    The Fall-Davis Report submitted to Congress recommends construction of the All-American Canal in California and a dam at Boulder Canyon in Nevada

  • June 5, 1922

    U.S. Supreme Court rules that the doctrine of prior appropriation can be applied between states where each of the states adheres to that doctrine. Wyoming v. Colorado, 259 U.S. 419.

  • 1922

    Colorado River Compact signed in Santa Fe, New Mexico 

  • 1923

    All states, except Arizona, ratify the Colorado River Compact

  • 1928

    Metropolitan Water District of Southern California formed to build the Colorado River Aqueduct to deliver Colorado River water to Southern California

  • 1928

    Boulder Canyon Project Act approves the 1922 Compact and authorizes construction of the All-American Canal and Boulder Dam (later renamed for President Herbert Hoover)

  • 1929

    California enacts the California Limitation Act, agreeing to limit its use of Colorado River water to 4.4 million acre feet per year

  • June 25, 1929

    President Hoover declares the Boulder Canyon Project Act to be in effect.

  • Oct. 13, 1930

    Arizona files suit in the Supreme Court against the Secretary of the Interior and the other six basin states seeking to block implementation of the Boulder Canyon Project Act.

  • Nov. 5, 1930

    Secretary of the Interior asks California to recommend an apportionment of its share of the Colorado River among water users in that state.

  • May 18, 1931

    The U.S. Supreme Court dismisses Arizona’s action without prejudice, holding that the Boulder Canyon Project Act is a valid exercise of congressional authority and does not purport to abridge any of Arizona’s rights. Arizona v. California (I), 283 U.S. 423.

  • Aug. 18, 1931

    California Seven Party Agreement among Palo Verde Irrigation District, Imperial Irrigation District, Coachella Valley County Water District, Metropolitan Water District of Southern California, City of Los Angeles, City of San Diego and County of San Diego establishes their relative priorities to Colorado River water.

  • Sept. 28, 1931

    Metropolitan Water District of Southern California enters into an amended contract with the Secretary of the Interior for delivery of Colorado River water in accordance with the California Seven Party Agreement.

  • Dec. 1, 1932

    Imperial Irrigation District enters into a contract with the Secretary of the Interior for delivery of Colorado River water in accordance with the California Seven Party Agreement. Contract also provides that the United States will construct Imperial Dam and the All-American Canal.

  • Feb. 7, 1933

    Palo Verde Irrigation District enters into a contract with the Secretary of the Interior for delivery of Colorado River water in accordance with the California Seven Party Agreement.

  • Feb. 15, 1933

    City of San Diego enters into a contract with the Secretary of the Interior for delivery of Colorado River water in accordance with the California Seven Party Agreement.

  • Feb. 14, 1934

    Arizona seeks to file a complaint in the U.S. Supreme Court to perpetuate testimony for a future action arising out of the Boulder Canyon Project Act to be brought against California and others.

  • May 21, 1934

    The Supreme Court denies Arizona’s motion. Arizona v. California (II), 292 U.S. 341.

  • Oct. 15, 1934

    Coachella Valley County Water District enters into a contract with the Secretary of the Interior for delivery of Colorado River water in accordance with the California Seven Party Agreement.

  • 1935

    President Franklin D. Roosevelt dedicates Hoover Dam

  • May 25, 1936

    The Supreme Court again denies Arizona’s motion, holding that the United States is an indispensable party to any adjudication of the Colorado River but that it cannot be joined without its consent. Arizona v. California (III), 298 U.S. 558.

  • 1937

    Congress approves Senate Document 80 authorizing construction of the Colorado-Big Thompson Project in Colorado

  • July 1, 1938

    Parker Dam is completed.

  • 1938

    The seven basin states organize the Committee of Fourteen, comprised of two representatives from each state, to address Colorado River issues

  • Jan. 7, 1939

    Metropolitan Water District of Southern California begins diverting water through the Colorado River Aqueduct.

  • 1940

    Reclamation completes construction of the All-American Canal

  • 1941

    Metropolitan Water District of Southern California completes construction of the initial Colorado River Aqueduct facilities

  • 1944

    Mexican Treaty signed whereby the U.S. commits to deliver 1.5 million acre feet of Colorado River water annually to Mexico

  • Jan. 3, 1944

    Nevada enters into a contract with the Secretary of the Interior for delivery of 300,000 af of Colorado River water.

  • Feb. 3, 1944

    United States and Mexico enter into a Treaty on the Utilization of Waters of the Colorado and Tijuana Rivers and of the Rio Grande. The Treaty guarantees Mexico 1.5 maf from the Colorado River in a normal water supply year. In the event of a surplus, Mexico is entitled to an additional 200,000 af. In the case of “extraordinary drought or serious accident to the irrigation system in the United States,” delivery of water to Mexico “will be reduced in the same proportion as consumptive uses in the United States are reduced.” United States agrees to construct Davis Dam to regulate deliveries to Mexico under the Treaty.

  • Feb. 9, 1944

    Arizona enters into a contract with the Secretary of the Interior for delivery of 2.8 maf of Colorado River water.

  • 1944

    Arizona ratifies the Colorado River Compact

  • Jan. 13, 1945

    The Colorado River Water Users Association formed at the Last Frontier Hotel in Las Vegas, Nevada 

  • June 11, 1945

    The Supreme Court retreats somewhat from its ruling in Wyoming v. Colorado, holding that “strict adherence to the priority rule” when equitably apportioning the flow of a river among prior appropriation states “may not be possible.” While priority remains the “guiding principle,” the Court identifies a number of additional factors that may be taken into account. “For example, the economy of a region may have been established on the basis of junior appropriations. So far as possible those established uses should be protected though strict application of the priority rule might jeopardize them.” Nebraska v. Wyoming, 325 U.S. 589, 618.

  • 1947

    Arizona seeks legislation authorizing the CAP. California opposes.

  • 1948

    Upper Colorado River Basin Compact signed by Arizona, Colorado, New Mexico, Utah and Wyoming 

  • 1949

    Upper Colorado River Commission established pursuant to the Upper Colorado River Basin Compact

  • Feb. 21, 1950

    Senate passes CAP legislation.

  • Dec. 15, 1950

    CAP legislation dies in House committee.

  • April 18, 1951

    House Committee on Interior and Insular Affairs indefinitely postpones action on CAP legislation “until such time as the use of the water in the Lower Colorado River Basin is either adjudicated, or a binding, mutual agreement as to the use of the water is reached by the states of the Lower Colorado River Basin.” (The Colorado River Board of California later boasted that it had been “instrumental” in achieving this result.)

  • June 5, 1951

    Senate passes CAP legislation for the second time.

  • Aug. 13, 1952

    Arizona files suit against California in Supreme Court to establish its right to Colorado River water.

  • June 1, 1954

    U.S. Supreme Court grants Nevada’s motion to intervene in Arizona v. California (IV).

  • Dec. 12, 1955

    U.S. Supreme Court denies California’s motion to join the four upper basin states in Arizona v. California (IV), but joins New Mexico and Utah as lower basin states.

  • 1956

    Colorado River Storage Project Act authorizes construction of Glen Canyon, Flaming Gorge, Navajo and Curecanti Storage Units 

  • 1962

    San Juan-Chama Project completed in New Mexico 

  • 1963

    U.S. Supreme Court decision in Arizona v. California

  • 1963

    Reclamation completes Glen Canyon Dam (Lake Powell)

  • June 1963

    In reaction to the Supreme Court’s opinion, California immediately announces that it will oppose authorization of the Central Arizona Project.

  • 1963

    Navajo Reservoir completed in New Mexico

  • 1964

    U.S. Supreme Court original decree in Arizona v. California

  • 1965

    Western governors establish the Western States Water Council to avoid interstate conflict by developing regional solutions to water problems

  • August 20, 1965

    Meeting in Washington, D.C., representatives of the seven basin states reach agreement on four general principles:

    • The Lower Basin’s temporary use of unused Upper Basin water will not jeopardize Upper Basin rights.

    • Importation of water from outside the Colorado River basin is essential and pending legislation should authorize construction of works to import at least 2.5 maf.

    • Imported water should be available no later than 1980, although there appears to be sufficient water to meet all needs, including CAP, until the 1990s.

    • Satisfaction of the Mexican treaty obligation should be a national obligation and the first priority for imported water.

  • 1968

    Colorado River Basin Project Act authorizes construction of the Central Arizona Project and six Upper Basin projects 

  • 1970

    Secretary of the Interior adopts Criteria for Coordinated Long-Range Operation of Colorado River Reservoirs 

  • 1971

    Southern Nevada Water Project completes Intake 1 at Lake Mead 

  • 1973

    U.S. and Mexico enter Minute 242 to the 1944 Treaty addressing salinity of water delivered to Mexico at Morelos Dam 

  • 1974

    Colorado River Basin Salinity Control Act authorizes salinity control projects above and below Imperial Dam, including the Yuma Desalination Plant

  • 1975

    Reclamation completes Westwide Study Report

  • 1977

    Lowest Colorado River natural flow since recordkeeping began in 1906

  • 1984

    Highest Colorado River natural flow since 1906

  • 1988

    Upper Colorado River Recovery Program authorized to protect endangered fish

  • 1990

    Fryingpan-Arkansas Project completed in Colorado

  • 1991

    Southern Nevada Water Authority formed

  • 1992

    Ten Tribes Colorado River Basin Partnership formed and formally join CRWUA. The ten tribes are: the Chemehuevi Indian Tribe; the Cocopah Indian Community; the Colorado River Indian Tribes; the Fort Mojave Indian Tribe; the Jicarilla Apache Tribe; the Navajo Nation; the Northern Ute Tribe; the Quechan Indian Tribe of the Fort Yuma Reservation; the Southern Ute Indian Tribe; and the Ute Mountain Ute Indian Tribe. 

  • 1993

    Central Arizona Project construction completed

  • 1996

    Department of the Interior issues its Record of Decision on the Operation of Glen Canyon Dam

  • 1998

    Imperial Irrigation District and San Diego County Water Authority negotiate water transfer agreement 

  • 1999

    Secretary of the Interior adopts regulations for offstream storage and release of unused apportionment enabling interstate water banking in the Lower Basin

  • 2000

    Multiyear Colorado River drought begins

  • 2000

    Metropolitan Water District of Southern California dedicates Diamond Valley Lake, the largest storage reservoir in Southern California

  • 2001

    Arizona and Nevada Water Banking Agreement signed

  • 2001

    Secretary of the Interior adopts Interim Surplus Guidelines establishing criteria for declaring surpluses in the Lower Basin states

  • 2002

    Southern Nevada Water Authority completes Intake 2 at Lake Mead

  • 2002

    Animas-La Plata Project begins construction in Colorado

  • 2003

    Quantification Settlement Agreement executed memorializing U.S. commitment to deliver water to California

  • 2004

    California and Nevada Water Banking Agreement signed

  • 2004

    Arizona Water Settlements Act enacted

  • 2005

    Lower Basin Multi-Species Conservation Program Implementing Agreement signed to protect habitat between Hoover Dam and U. S. - Mexico boundary

  • May 2, 2005

    Secretary of the Interior announces her intent to develop guidelines for conjunctive management of Lakes Powell and Mead and shortage sharing in the Lower Basin by December 31, 2007, and initiates a public process toward that end. The Basin States are encouraged to reach agreement.

  • Feb. 3, 2006

    Basin States submit a Preliminary Proposal Regarding Colorado River Interim Operations, including coordinated management of Lake Powell and Lake Mead and shortage guidelines for the lower basin.

  • 2006

    U.S. Supreme Court enters its Consolidated Decree in Arizona v. California

  • 2007

    Secretary of the Interior adopts Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead

  • 2009

    Imperial Irrigation District completes 23-mile concrete lined section of All American Canal

  • 2010

    Magnitude 7.2 Easter Sunday earthquake damages Mexico irrigation systems prompting Minute 318 to the 1944 Treaty, allowing Mexico temporary water storage in Lake Mead

  • 2012

    U.S. and Mexico enterMinute 319 to the 1944 Treaty establishing criteria to share in water surpluses and shortages

  • 2012

    Glen Canyon Dam High Flow Experimental Flow Release

  • 2012

    Reclamation releases Colorado River Basin Water Supply and Demand Study

  • 2014

    Environmental pulse flow and base flow, allowed by Minute 319 to the 1944 Treaty, are released through the Colorado River channel in Mexico to start new vegetation for wildlife habitat

  • 2019

    The Drought Contingency Plan is passed by all seven states and Congress.